1. Field of the Invention
The present invention relates to detection of a gas using a MEMS gas sensor, and particularly relates to prevention of poisoning by organic solvent, silicone vapor, or the like.
2. Description of Related Art
It is known that silicone vapor poisons a gas sensor. Known countermeasures against this problem include a technique for removing poisonous gas using a filter made of activated carbon or the like (Patent Document 1: JP 3087982) and a technique for causing poisonous gas to decompose on a surface portion of a gas sensor (Patent Document 2: JP 4401445). Furthermore, the present inventor found that, in the case of a MEMS gas sensor, organic solvent such as ethanol also acts as poisonous gas.
Although a filter is effective for the prevention of poisoning, when the filter is exposed to a high concentration of poisonous gas for a long period of time, the poisonous gas passes through the filter and reaches inside the gas sensor.